The invention relates to a method and a forming machine suitable for manufacturing a product having various diameters from a workpiece, such as a metal cylinder or plate, in which the workpiece is clamped down in a clamping device, the workpiece and a first tool are rotated about an axis of rotation relative to each other, the workpiece is deformed by means of said first tool by placing the tool into contact with the workpiece and moving the workpiece and/or the tool in a direction along, i.e. parallel to or having a component parallel to, the axis of rotation.
Such a method and apparatus are known, e.g. from EP 0 916 426. Said publication describes how one end of a cylindrical workpiece is worked by clamping down said workpiece in a clamping device (indicated by numeral 12 in FIG. 1 of EP 0 916 426) and deforming said ends by means of three forming rollers (28), which are mounted on a rotary member (24). Said forming rollers (28) rotate in the same plane and are pressed against the workpiece at three locations which are evenly distributed over the circumference of the workpiece, after which said rollers move along a number of paths along the workpiece so as to deform the workpiece in steps.
For the sake of completeness, attention is drawn to DE 23 27 664 and DE 1964 401, in which methods and apparatuses are described for flow pressing cylindrical tubes, i.e. tubes having a constant diameter. The methods and apparatuses according to these documents are unsuitable for manufacturing a product having various diameters. JP 2000301246 also relates to a method and apparatus for flow pressing cylindrical tubes.